A multi-branch receiver is sometimes utilized in radio communication systems to receive a receive signal. A multi-branch receiver includes a plurality of receiver branches. Each receiver branch of the multi-branch receiver includes circuitry, or other functionality, of at least significant portions of a radio receiver. The receiver branches are coupled to a signal combiner. The signal combiner selectively combines together the receive signal received at selected ones of the receiver branches.
Improved reception of the receive signal is permitted by appropriate combination of the receive signal received at one or more of the receiver branches. For instance, the receive signal received at certain of the various receiver branches might, for instance, possess better signal characteristics than the receive signal received at certain others of the receiver branches. Selective combination of the receive signal received at the receiver branches exhibiting good quality permits a combined signal to be formed.
As signal characteristics of the receive signal change at the various receiver branches, the receiver branches selected from which to combine the receive signal can be changed, as appropriate.
The multi-branch receiver is advantageously utilized in a fixed-infrastructure such as a base station of a cellular communication system. When forming the portion of a cellular base station, an uplink signal transmitted to the base station by a mobile terminal forms the receive signal received at various branches of the multi-branch receiver.
An antenna matrix, such as a Butler matrix, for instance, can be used in conjunction with the multi-branch receiver. Different ones of the receiver branches are connected to the antenna matrix.
The receiver having two or more separate branches can sometimes provide improved receiver performance. The receive signal received at different ones of the receiver branches does not necessarily possess identical characteristics. The receive signal received at one receiver branch might exhibit better characteristics than the receive signal received at another receiver branch. The signal characteristics of the receive signals received at the various receiver branches might change over time. By selectively combining the receive signal received at various ones of the receiver branches, the resultant signal sometimes permits a more accurate re-creation of the signal transmitted to the receiver.
Different antenna patterns formed by different configurations of the antenna matrix cause the receive signals applied to the different receiver branches to be of different characteristics. The signal characteristics of the receive signal received at certain of the receiver branches are likely to be better than the signal characteristics of the receive signal received at others of the receiver branches. As the mobile terminal moves throughout an area encompassed by the cellular base station, uplink signals transmitted by the mobile terminal unit form the receive signal which is received at different signal strengths, and other signal qualities, at different ones of the receiver branches.
While use of the multi-branch receiver improves the possibility of accurately re-creating the uplink signal transmitted thereto, the receive signal received at each receiver branch must be separately processed. Substantial amounts of processing are required to process the receive signal in each receiver branch. The processing power required of the multi-branch receiver can become quite significant, particularly when the number of branches of which the multi-branch receiver is formed is large. Such processing power requires the allocation of significant resources to process the separate signals and to selectively combine signals from various ones of the receiver branches.
A manner by which the processing required of the multi-branch receiver can be reduced while maintaining the improved receiver operation permitted of the multi-branch receiver would be advantageous.
It is in light of this background information relating to multi-branch receivers that the significant improvements of the present invention have evolved.